Children with ADHD (combined or hyperactive-impulsive subtype) by Parent and Teacher Rating Scales, history, and interview who do not have a medical or neurologic problem that influences eating, who are not on medication for ADHD or another medication that may influence eating, aged 5-13 years with a sibling in the same age range meeting the same criteria but without ADHD. This sibling must have a normal Parent Rating Scale and not have been held back in school or been on medication or diagnosed with a learning, developmental, or neuropsychiatric disorder. Controls must meet the same criteria, and may not have a first-degree relative with ADHD. All participants must have a normal intellect, and may not have an autistic spectrum disorder or major depression.